function rollon() {
  if (window.event.srcElement.className == "B-out") {
     window.event.srcElement.className = "B-over";
//    sub3.style.display = "none";
  } 
}
Rollover.onmouseover = rollon;

function rolloff() {
  if (window.event.srcElement.className == "B-over") {
     window.event.srcElement.className = "B-out";
  }
  if (window.event.srcElement.className == "B-down") {
     window.event.srcElement.className = "B-out";
  } 
}
Rollover.onmouseout = rolloff;

function press() {
  if (window.event.srcElement.className == "B-over") {
     window.event.srcElement.className = "B-down";
  }
}
Rollover.onmousedown = press;

function unpress() {
  if (window.event.srcElement.className == "B-down") {
     window.event.srcElement.className = "B-over";
  } 
}
Rollover.onmouseup = unpress;